1. Field of the Invention
The present invention relates to cameras and, more particularly, to multi-mode cameras.
2. Description of the Related Art
Video cameras are often used for security or surveillance purposes. The use of video cameras for security purposes by consumers and businesses has grown dramatically in recent years. The stored video from these video cameras is often analyzed after a crime or accident. In other words, the stored video is analyzed as part of an investigation concerning a crime or accident or some associated lawsuit to determine the facts surrounding the incident. High resolution security cameras are rarely used since the quantity of data they produce is enormous and thus require expensive storage media and high bandwidth data networks. As a result, most video cameras use a broadcast resolution or less so that the amount of storage media needed is economically feasible. Hence, the resolution utilized is, for example, 720xc3x97480 pixels which is in accordance with the National Television System Committee (NTSC) standard. Typically, the storage media is videotape because of its low cost.
Although the stored video in this regard is useful to view incidents that have been captured on the stored video, often there is a need for capturing higher resolution and/or higher quality images so that the stored data contain more detail and useful information for investigations. Currently, security cameras are not able to offer or provide the benefits of both high resolution and/or higher quality images and manageable amounts of data storage.
Thus, there is a need for a security camera that can yield high resolution images without requiring excessive amounts of data storage.
Broadly speaking, the invention relates to an image acquisition system employing a digital pixel sensor (DPS) that supports multiple modes of operation. The image acquisition system can be used to acquire and store not only video images but also still images. The image acquisition system is typically part of or within a video camera, but could also itself be a digital camera.
According to one aspect of the invention, when the image acquisition system (e.g., digital camera) operates in a video mode, video images with low or moderate resolution and/or quality are acquired, and when the image acquisition system operates in a still mode, still images are acquired. The acquired still images through a DPS are generally of high quality and/or high resolution. The quality of an image used herein means that the image is relatively independent of ambient lighting conditions and has very high dynamic range so that details in very dark or bright areas are preserved. Generally, the images are digital images of objects or scenes.
According to another aspect of the invention, the image acquisition system (e.g., a digital camera) includes a digital pixel sensor, a memory, and an image processing unit all on a single integrated circuit (chip). Image data obtained from the image sensor and stored in the memory can be processed on-chip by the image processing unit to thus acquire and output not only video images but also still images using the same image acquisition system. In one implementation, the image acquisition system can produce high quality still images interleaved in real time with broadcast quality video images.
The invention can be implemented in numerous ways, including as a method, system and computer readable medium. Several embodiments of the invention are discussed below.
As a method for operating an electronic image capturing system having a single image sensor array, one embodiment of the invention includes at least the acts of: capturing and storing a first series of video images using the image sensor array; capturing and storing a first still image using the image sensor array; capturing and storing a second series of video images using the image sensor array; and capturing and storing a second still image using the image sensor array.
As a method for operating an electronic image capturing system having a single image sensor array, another embodiment of the invention includes at least the acts of: operating the electronic image capturing system in a first mode so that video images are captured and stored; periodically switching the electronic image capturing system to a second mode; operating the electronic image capturing system in the second mode so that a still image is captured and stored; and thereafter switching the electronic image capturing system back to the first mode.
As a single-chip image acquisition system having a video mode and a still mode, one embodiment of the invention includes at least: a digital sensor array having a plurality of pixel sensors, the digital sensor array outputs analog signals representing at least one image and having supporting circuitry for receiving and converting the analog signals to sensor digital image information; and an image processor operatively connected to the digital sensor array, the image processor operates to produce video images from the sensor digital image information when in the video mode, and operates to produce still images from the sensor digital image information when in the still mode. The digital sensor array and the image processor are provided on a single integrated circuit chip.